What is a correct way of doing it?
The way you showed is a possible way. You could also use:
vector<vector<int>> myvect = { {10,20,30,40},
{50,60,70,80} };
vector<vector<int>> myvect{ vector<int>{10,20,30,40},
vector<int>{50,60,70,80} };
The first one constructs a std::initializer_list<std::vector<int>>
where the elements are directly initialized from the inner braced-initializer-lists. The second one explicitly constructs temporary vectors which then are moved into a std::initializer_list<std::vector<int>>
. This will probably not make a difference, since that move can be elided.
In any way, the elements of the std::initializer_list<std::vector<int>>
are copied back out into myvect
(you cannot move out of a std::initializer_list
).
And how can i iterate through it using for?
You essentially have a vector of vectors, therefore you need two loops:
for(vector<int> const& innerVec : myvect)
{
for(int element : innerVec)
{
cout << element << ',';
}
cout << endl;
}
I refrained from using auto
to explicitly show the resulting types.
And by the way what does this mean ?
This is probably a typo. As it stands, it's illegal. The declaration vector<int> myvect[5];
declares an array of 5 vector<int>
. The following list-initialization therefore needs to initialize the array, but the elements of this list are not implicitly convertible to vector<int>
(there's a ctor that takes a size_t
, but it's explicit).
That has already been pointed out in the comments of that side.
I guess the author wanted to write std::vector<int> vArray = {3, 2, 7, 5, 8};
.